Filipino ring icon Manny Pacquiao comprehensively dismantled American Chris Algieri to retain his World Boxing Organization (WBO) welterweight title at the Cotai Arena in Macao on Sunday.

Pacquiao dropped Algieri to the canvas six times during the 12-round contest to win an overwhelming unanimous decision (119-103, 119-103, 120-102).

Algieri, the unbeaten WBO light welterweight champion, was outclassed from the start, with the eight-division world champion Pacquiao knocking the Long Islander down in the second round, twice in both the sixth and ninth rounds, and ­finally again in the 10th.

Pacquiao was landing punches at will as the quick ­Algieri tried to run, slip and hide from the onslaught.

But the congressman from Sarangani Province really turned it when he smashed Algieri to the canvas with a devastating straight left in the sixth.

The American only beat the count and dropped to one knee moments later as blows rained in from all angles. He somehow survived and was knocked down twice more in the ninth and then again in the 10th, with one left sending him sprawling across the ring and head over heels backward into the corner.

Algieri holds a master's degree and an ambition to become a doctor once his boxing days are over. All week in the buildup, his trainer Tim Lane had been declaring that he would destroy Pacquiao by "master boxing."

They proved hollow words and Pacquiao's Hall of Fame trainer Freddie Roach mocked them afterward.

"The master boxer was given a master class by Professor Pacquiao," Roach said.

Pacquiao's victory will inevitably heighten calls for him to face the unbeaten Floyd Mayweather in what could be the first billion-dollar fight in history.

Also on Sunday, China's double Olympic gold medal-­winning flyweight Zou Shi­ming dismantled an experienced and durable Thai opponent over 12 rounds to earn a world title shot next year.

In just his sixth fight the Chinese star gave his best performance since turning pro after winning gold at London 2012.

The unbeaten Kwanpichit Onesongchaigym by contrast was in his 28th pro bout and raised cheers among the huge Filipino contingent with his uncanny resemblance to their hero Pacquiao.

But that was where the similarity ended for the man dubbed "Mini-Manny" as he was battered by the lightning quick Zou and dropped to the canvas five times in all, twice in the second round, but bravely got back up on each occasion to see out the full distance.

Kwanpichit was also ­deducted a point for a series of low blows and lost an overwhelming unanimous decision (119-104, 120-103, 119-104).

This was a final eliminator for the WBO world flyweight championship, making Zou mandatory challenger to title holder Juan Francisco Estrada of Mexico in a fight likely to take place in spring next year in Macao.